Vehicle heating systems, such as cabin climate control systems, often rely on waste engine heat as a heat source. However, under some conditions there may be insufficient waste engine heat, thus leading to customer discomfort. As a result, fuel burning heaters have been used to generate heat that can be provided to the climate control system of the vehicle. One such example is described in U.S. Pat. No. 6,131,553 in which a combustion heater is positioned in an engine intake system. The heater may include a coolant passage traveling therethrough. The coolant passage may be configured to flow coolant through the combustion heater to a car room heater.
Rather than the above approaches, various approaches are proposed to improve system performance by coordinating the fuel burning heater operation with engine operation in an interactive system. For example, one approach includes a method, comprising: during stopped engine operation, burning fuel in an engine intake heater to generate heated gas, the heated gas bypassing engine cylinders via an exhaust gas recirculation passage; and during combusting engine operation, burning fuel in the engine intake heater to generate heated gas, and flowing the heated gas through combusting engine cylinders.
In this way, it is possible to transfer heat from the heater's heated gas (e.g., to a climate control system) while also taking advantage of the engine's exhaust gas recirculation ducting to transport the heated gas to the exhaust. As one example, the heated gas can take advantage of intake air system heat-exchangers, such as intercoolers and/or exhaust gas recirculation cooler, already present for cooling boosted intake air or exhaust gas recirculation gasses during engine operation. Thus, during engine off conditions, the intercooler and/or EGR cooler, along with the EGR passage, enable the system to not only transfer heat to the engine coolant and thus the cabin, but also provide the gas handling system itself.
Further still, such operation re-uses any remaining heat in the heated gas to maintain temperature of emission control devices in the engine exhaust, which can reduce emissions on subsequent engine starts.
Additionally, when the engine is combusting, but still cold, the heater's heated gas can not only transfer heat to the climate control system, it can also be used to increase the intake air temperature fed to the combustion cylinder thus improving engine combustion stability and fuel economy, particularly at cold ambient temperatures.
Further, this ability to heat an emission control device such as a catalyst with fuel and air combusted in the intake system without the heated gas passing through the engine enables initial emission control device (e.g., catalyst) heating to be performed with or without the engine running. One benefit that this yields is that the engine may be used an effective vacuum source for various vehicle operations such as brake boost even during a cold engine start.
As another example, a vehicle is provided. The vehicle includes a fuel burner positioned in an intake system and a heat-exchanger positioned downstream of the fuel burner. The vehicle also includes an exhaust gas recirculation (EGR) passage fluidly coupling the intake system to an exhaust system and a control system configured to initiate generation of heated gas in the fuel burner and flow the heated gas to the heat-exchanger and through the EGR passage to the exhaust system. It will be appreciated that a pressure gradient may be generated to flow the heated gas to the heat exchanger. The pressure gradient may be generated via a blower fan included in the vehicle, the blower fan having an outlet positioned in the intake system upstream of the fuel burner. Alternatively, or additionally, the pressure gradient may be generated through pulsing of the fuel burner, where the pulsing of the fuel burner enables the system to act as a pulse jet engine.
Again, the above configuration can enable improved coordination between the fuel burner and the engine intake and exhaust ducting, thus enabling improved cabin climate control as well as improved engine performance.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.